_____________________________________________________________________________________________________ *Corresponding author: E-mail: oc.soludo@unizik.edu.ng; J. Adv. Biol. Biotechnol., vol. 27, no. 2, pp. 149-158, 2024 Journal of Advances in Biology & Biotechnology Volume 27, Issue 2, Page 149-158, 2024; Article no.JABB.107825 ISSN: 2394-1081 Microbial Populations of Agricultural Soil Polluted With Crude Oil Soludo, O. C. a* , Orji, M. U. a , Anaukwu , C. G. a , Anyaoha, V. I. a , Ajogwu, T. M. C. a and Eze, H. C. a a Department of Applied Microbiology and Brewing, Nnamdi Azikiwe University, Awka, P.M.B., 5025, Nigeria. Authors’ contributions This work was carried out in collaboration among all authors. All authors read and approved the final manuscript. Article Information DOI: 10.9734/JABB/2024/v27i2706 Open Peer Review History: This journal follows the Advanced Open Peer Review policy. Identity of the Reviewers, Editor(s) and additional Reviewers, peer review comments, different versions of the manuscript, comments of the editors, etc are available here: https://www.sdiarticle5.com/review-history/107825 Received: 24/08/2023 Accepted: 29/10/2023 Published: 28/02/2024 ABSTRACT Crude oil pollution of the soil has become a public health and environmental concern. It impacts soil microbial diversity and population. In this study, the microbial population of crude oil polluted soil and unpolluted were determined. The potential for the indigenous organisms to utilize hydrocarbon as a source of carbon was also determined. A soil sample was obtained from an agricultural field and polluted with a defined amount of crude oil for 12 weeks. The microbial population in the polluted soil and unpolluted soil were estimated and characterized following standard microbiological methods. The heterotrophic bacterial and fungal counts in the unpolluted and polluted soil were 6.5 x 104CFU/g and 4.7 x 104 CFU/g, and 6.3 x104 CFU/g and 3.5 x104 CFU/g respectively. Total hydrocarbon utilizing bacterial and fungal counts in the polluted soil was 4.6 x 104 CFU/g and 2.8 x 104 CFU/g. The genera of bacteria and fungi identified in the soil samples were Bacillus, Enterococcus, Micrococcus, Escherichia, Pseudomonas, Staphylococcus, Serratia, Proteus, Klebsiella, Arthrobacter, Aspergillus, Candida, Penicillium, Fusarium, Trichoderma, Cladosporium and Hyphopichia. The preliminary screening for hydrocarbon utilization shows that Original Research Article